This competitive renewal application describes experiments which continue this laboratory's investigation into hormonal immunoregulation using insulin and the lymphocyte insulin receptor as the model system. The specific aims flow directly from questions and issues raised in the initial grant application. The first specific goal of the new protocol examines additional levels of lymphocyte insulin receptor regulation. At the cellular level, the amount of the ligand available to serve as regulatory molecules will be ascertained by examining insulin degradation from cell membrane and ligand-receptor complex internalization by performing timed binding studies, immuno-absorbent chromatography, and rebinding. The role of thelysosome in receptor regulation will be examined withlysomotropic agents, chloroquine and NH(4)Cl. To examine whether receptor regulation can occur through insertion of ligand released from the lysosome, experiments using incorporation of ( 3H)-leucine and affinity chromatography are planned. Defects in insulin receptor binding to the lymphocyte insulin receptor have recently been described by this laboratory in Type II diabetics and non-diabetic, obese patients. Protocols are designed which pursue further the nature of the defects as plasma inculin will be changed subacutely in diabetics, obese subjects, and normals to examine the role of plasma insulin in receptor regulation in patients with altered carbohydrate metabolism. To examine the mechanism of ligand regulation of the lymphocyte insulin receptor, hormonal levels will be altered acutely using the glucose clamp technique. The second specific aim seeks to expand our knowledge of the immunomodulating role of insulin and thelymphocyte insulin receptor. Questions concerning insulin supported lactate metabolism raised during the initial grant period are answered by studing the red/ox poise of the receptor bearing lymphocyte as influenced by insulin. The presence and importance of the receptor for T helper function for B cell receptor generation and antibody production are investigated. Finally the role of insulin in supporting receptor positive B cell antibody production is determined using a quantitative assay of immunoglobulin synthesis by immunoprecipiration and SDS-polyacrylamide gel electrophoresis.